FIG. 1 shows a structure diagram of a mouse key identification circuit according to a conventional art FIG. 2 shows a structure diagram of a Light-Emitting Diode (LED) driver circuit of the mouse key identification circuit shown in FIG. 1. FIG. 3 shows a driving waveform diagram of an LED port in the LED driver circuit shown in FIG. 2.
In a common implementation scheme of an optical mouse implemented by an existing technology, an application circuit of a key switch and the scroll wheel switch as shown in FIG. 1 generally includes: KL/KM/KR ports used for three keys, Z1/Z2 ports used for the scroll wheel, and an LED drive port for driving an LED light.
FIG. 3 shows a driving waveform of an LED port in the application circuit of the LED port shown in FIG. 2. In the driving waveform diagram of the LED port, when the LED port outputs a low level, an LED is driven to light. When the output of the LED port is a high resistance, the LED does not light. At this moment, since an external LED is connected to the power supply, the level of the LED port would become a high level. In FIG. 2, Rn represents a current-limiting resistor and D represents an LED.
For the key, the scroll wheel and the LED driver of the mouse implemented by the existing technology above, at least six signal collection ports (port 1, port 2, port 3, port 4, port 5 and an LED port) are needed to output to a processor. For a mouse processor circuit integrated with a photoelectric sensor, the cost of implementing an overall solution of the mouse is higher if there are more ports; Therefore, to reduce the number of the ports of the mouse processor circuit integrated with a photoelectric sensor is significant to reduce the cost of the mouse.
For the problem of big package and high cost of a mouse circuit existing in the mouse key identification circuit implemented by the relevant art due to the requirement of excessive signal collection ports, no effective solution has been proposed so far.